To use dlopen, you need to use Emscripten's linking support

when i sending message by websocket.jslib Web Console show erros:To use dlopen, you need to use Emscripten’s linking support

You must enter your BUILD and Run tab, then select the DEVELOPER BUILD (development build), when you run your app like mines that were a WEB GL app then a console will pop up with any error you can get… I ALWAYS GET THE ERROR use emscripten’s linking BUT AFTER I make a Developer build I could see an error on the console called CANT IMPORT USER32.DLL that was my problem that DLL cannot run on a browser so I disable IT, that way I Solve my issue. Thanks hope this may help others.
Regards Daniel